Origin of the nonmonotonic DIVA error shoulder

Determine the origin of the nonmonotonic shoulder in the DIVA angular-error curve for the Permalloy disk with aspect ratio t/R = 0.0125, and establish whether its position tracks the parameter \mathcal{A} by examining an additional aspect ratio.

Background

For the Permalloy disk with aspect ratio t/R = 0.0125, the DIVA approximation exhibits a shoulder near reduced core displacement s \approx 0.8 before its angular error increases more steeply. The paper reports this behavior as an observation but does not explain its physical or mathematical origin. The authors identify a concrete route toward resolving the issue: simulations or analysis across a third aspect ratio could test whether the shoulder position is controlled by the deformation localization parameter \mathcal{A}.

References

We report this shoulder as an observation; its origin is not established here, and resolving it would require sweeping a third aspect ratio to test whether its position tracks $\mathcal{A}$.

— The Deformed Image Vortex Ansatz: A Perturbation-Aware Description of Magnetic Vortices in In-Plane Fields  (2608.17840 - Coppée et al., 18 Aug 2026) in Section 3.2, subsection “Mean angular error”